Method for detecting Pb < 2 + > in glyceryl triacetate for cigarettes

Abstract

The invention relates to the technical field of detection of materials for cigarettes, in particular to a method for detecting Pb < 2 + > in glyceryl triacetate for cigarettes. The method comprises the following steps: 1, adding an actual sample into a centrifugal tube, and then adding a nitric acid solution with the mass fraction of 5%; 2, an APDC solution with the concentration of 0.01 M is added, the ratio of the concentration of APDC to the concentration of Pb < 2 + > in an actual sample solution is made to be larger than 100: 1 all the time, and it is ensured that Pb < 2 + > is fully complexed; step 3, adding N, N-dimethyl benzylamine; 4, sodium hydroxide with the concentration being 200 g / L is added; 5, centrifuging, transferring 200 microliters of an upper-layer N-N dimethyl benzylamine phase into a centrifugal tube, and adding a nitric acid solution with the mass fraction of 5% for dilution; step 6, detecting Pb < 2 + > in the diluted solution by adopting square wave anodic stripping voltammetry; the detection method has the advantages of simple pretreatment process, accurate detection result and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of tobacco material detection, and in particular to a method for detecting Pb in tobacco triacetin. 2+ method. Background Art

[0002] Glyceryl triacetate is a colorless, viscous liquid under normal conditions. It improves filter rod assembly properties and thermal collapse resistance and is the primary plasticizer used in the production of acetate filter rods for cigarettes. Typically, triacetin is prepared by heating glycerol and acetic acid over an acidic catalyst, removing the generated water with a dehydrating agent, and producing a semi-finished product. This is then deeply esterified with acetic anhydride to produce a crude product, which is then refined through deacidification and decolorization. Commonly used dehydrating agents include esters such as benzene, toluene, and ethyl acetate, as well as cyclohexane. During this process, the raw acetic acid may contain impurities such as formic acid, propionic acid, ethanol, and acetaldehyde, while the glycerol and reaction water may also contain heavy metals. In the esterification step of triacetin production, the dehydration reaction temperature is limited by the boiling point of acetic acid and is typically set at 105°C. Consequently, a large amount of organic compounds remain in the crude product. Even after further distillation and rectification, the finished triacetin may contain components that affect its quality and safety. When smoking a cigarette, the hot mainstream smoke can cause the filter tip to reach temperatures exceeding 80°C. Residual organic compounds such as triacetin in the filter may be distilled out, and heavy metal particles can also be present in the smoke aerosol and inhaled. Currently, the industry standard YC / T 144-2017 sets limits on the content of heavy metals (arsenic and lead), with the limit for lead being ≤5.0mg / kg.

[0003] Currently, established technologies for detecting lead ions in samples include inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectroscopy (AAS), and fluorescence spectroscopy (FS). These techniques offer high sensitivity and selectivity. However, these technologies are subject to relatively high equipment and measurement costs, and drawbacks such as complex operating procedures, prolonged measurement times, complicated sample preparation, and susceptibility to interference from other metal ions have hindered widespread adoption. Therefore, it is crucial to develop methods for detecting heavy metal lead ions that offer advantages such as high sensitivity, simplicity, low cost, ease of sample preparation, and on-site detection. Summary of the Invention

[0004] The present invention aims to solve the problems of the existing method for determining lead ions in triacetin, which relies on the use of complex laboratory-based equipment. However, the equipment is expensive, requires laborious pretreatment, has high operating costs, requires professional operators, is not easy to carry, and has cumbersome and time-consuming procedures. A method for detecting Pb in triacetin for tobacco is provided. 2+ method.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for detecting Pb in triacetin 2+ The method comprises the following steps:

[0006] Step 1: Add the actual sample to a centrifuge tube, and then add a 5% nitric acid solution to obtain a diluted sample solution;

[0007] Step 2: Add 0.01M APDC solution to make the concentration of APDC in the actual sample solution equal to that of Pb 2+ The concentration ratio is always greater than 100:1, ensuring that Pb 2+ is fully complexed;

[0008] Step 3: Add NN dimethylbenzylamine. At this time, the solution is one phase, and NN dimethylbenzylamine extracts the lead chelate in the actual sample solution.

[0009] Step 4: Add 200g / L sodium hydroxide. At this time, the upper layer appears NN dimethylbenzylamine phase, which contains Pb 2+ chelates;

[0010] Step 5: Centrifuge, transfer 200 μL of the upper NN-dimethylbenzylamine phase into a centrifuge tube, and dilute with 5% nitric acid solution;

[0011] Step 6: Use square wave anodic stripping voltammetry to detect Pb 2+ .

[0012] As a further limitation of the technical solution of the present invention, in step 1, the mass volume ratio of the actual sample to the nitric acid solution is 1 g:8 mL.

[0013] As a further limitation of the technical solution of the present invention, the volume ratio of the added APDC solution, NN dimethylbenzylamine, and sodium hydroxide solution is 2:5:10.

[0014] As a further limitation of the technical solution of the present invention, the volume ratio of the nitric acid solution added in step 5 to the volume ratio of the nitric acid solution added in step 1 is 40:13.

[0015] As a further limitation of the technical solution of the present invention, the working electrode used in step 6 is C-SPE-1 or C-SPE-2. The reference electrode is Ag / AgCl, and the counter electrode is conductive carbon paste.

[0016] As a further limitation of the technical solution of the present invention, in step six, bismuth nanoparticle material is used to modify the electrode surface.

[0017] As a further limitation of the technical solution of the present invention, in step six, the bismuth nanoparticle-modified electrode adopts an in-situ modification method.

[0018] As a further limitation of the technical solution of the present invention, the square wave anodic stripping voltammetry detection parameters in step six are: deposition voltage -1.2V, deposition time 180s, scanning voltage range -1.0 to -0.4V, frequency 25Hz, and amplitude 0.025V.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The pretreatment variable hydrophilic solvent-liquid microextraction process of the present invention eliminates the complex and dangerous steps in microwave digestion, such as the large amount of microwave digestion reagent used and the long digestion time; the easy generation of a large amount of foam overflow in the early stage of digestion; the high temperature that easily causes the loss of volatile elements (As, Hg, etc.); the high energy consumption; the frequent generation of a large amount of harmful gases that pollute the environment; and the digestion process is carried out in an open system, which is prone to cross contamination.

[0021] 2. Compared with other liquid-liquid extraction methods, the variable hydrophilic solvent-liquid microextraction method of the present invention is simple to operate, has high extraction efficiency, good enrichment effect, less time consumption, and requires less organic solvent. It is an environmentally friendly pretreatment technology.

[0022] 3. Compared with the traditional detection equipment ICP-MS, the detection equipment used in the present invention is small, easy to carry, and inexpensive. The detection process is efficient and agile, the detection environment requirements are low, and no carrier gas is required, and the requirements for detection personnel are low. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The different concentrations of Pb in triacetin in Example 1 2+ The SWASV response.

[0024] Figure 2 The different concentrations of Pb in triacetin in Example 1 2+ The standard curve of DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to specific embodiments.

[0026] Example 1

[0027] ① Add 0.5g of actual sample to a 10mL centrifuge tube, then add 4mL of 5% nitric acid solution to obtain a diluted sample solution; ② Add 0.5mL of Pb 2+ Standard solution, so that the actual sample solution Pb 2+The concentrations of Pb were 2, 4, 8, 12, and 16 mg / kg respectively; ③ 0.2 mL of 0.01 M APDC solution was added to make the concentration of APDC in the actual sample solution consistent with that of Pb 2+ The concentration ratio is always greater than 100:1, ensuring that Pb 2+ was fully complexed; ④ 0.5 mL of NN dimethylbenzylamine was added. At this time, the solution was one phase, and NN dimethylbenzylamine achieved the extraction of lead chelates in the actual sample solution; ⑤ 1.0 mL of 200 g / L sodium hydroxide was added. At this time, NN dimethylbenzylamine phase appeared on the upper layer. The NN dimethylbenzylamine phase contained Pb 2+ 6. Centrifuge, carefully remove 200 μL of the upper NN dimethylbenzylamine phase into a centrifuge tube, and add 1.3 mL of 5% nitric acid solution; 7. Use square wave anodic stripping voltammetry to detect Pb 2+ The electrode type used is C-SPE-1, and bismuth nanoparticle material is used to modify the electrode surface. The bismuth nanoparticle modified electrode adopts the in situ modification method.

[0028] The method was used to detect Pb in triacetin 2+ The contents are shown in the following table:

[0029] Table 1 Method recovery

[0030]

[0031] Comparative Example 1

[0032] For the detection of Pb in tobacco triacetin 2+ The method is the same as that in Example 1, except that the pre-treatment steps and the detection method are different. The pre-treatment steps adopted in this comparative example are as follows:

[0033] The pretreatment and detection methods adopted the inductively coupled plasma mass spectrometry method of YC / T 316-2014 Determination of chromium, nickel, arsenic, selenium, cadmium, mercury and lead residues in tobacco materials.

[0034] Table 2 Method recovery

[0035]

[0036] Compared with Comparative Example 1, the pre-treatment variable hydrophilic solvent-liquid microextraction process of the present invention eliminates the complicated and dangerous steps in microwave digestion, such as the large amount of microwave digestion reagent used and the long digestion time; a large amount of foam is easily generated and overflowed in the early stage of digestion; high temperature easily causes the loss of volatile elements (As, Hg, etc.); large energy consumption; often produces a large amount of harmful gases, polluting the environment; the digestion process is carried out in an open system, which is easy to cause cross contamination, etc. Compared with other liquid-liquid extraction methods, the variable hydrophilic solvent-liquid microextraction method is simple to operate, has high extraction efficiency, good enrichment effect, less time consumption, and requires less organic solvent. It is an environmentally friendly pre-treatment technology. Compared with the traditional detection equipment ICP-MS, the detection equipment used in the present invention is small, easy to carry, and low in price. The detection process is efficient and agile, has low requirements for the detection environment and does not require the use of carrier gas, and has low requirements for detection personnel.

Claims

1. A method for detecting Pb in triacetin for tobacco 2+ method, It is characterized in that The following steps are involved: Step 1, adding the actual sample into a centrifuge tube, and then adding a nitric acid solution with a mass fraction of 5% to obtain a diluted sample solution; Step 2: Add 0.01 M APDC solution to make the concentration of APDC in the actual sample solution consistent with that of Pb 2+ The concentration ratio is always greater than 100:1, ensuring that Pb 2+ is fully complexed; Step 3, adding NN dimethylbenzylamine, at this time, the solution is one phase, and NN dimethylbenzylamine realizes the extraction of lead chelate in the actual sample solution; Step 4: Add 200 g / L sodium hydroxide. At this time, the upper layer appears NN dimethylbenzylamine phase, which contains Pb 2+ Chelates; Step 5: Centrifuge, transfer 200 μL of the upper NN-dimethylbenzylamine phase into a centrifuge tube, and dilute with 5% nitric acid solution; Step 6: Detect Pb by square wave anodic stripping voltammetry in the diluted solution. 2+ .

2. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that The mass volume ratio of the actual sample to the nitric acid solution in step 1 is 1 g:8 mL.

3. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that The volume ratio of the added APDC solution, NN dimethylbenzylamine, and sodium hydroxide solution is 2:5:

10.

4. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that The volume ratio of the nitric acid solution added in step 5 to the nitric acid solution added in step 1 is 40:

13.

5. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that In step six, HAc-NaOH buffer with a pH of 5.7 is used.

6. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that The electrode type used in step six is ​​C-SPE-1 or C-SPE-2.

7. A method for detecting Pb in triacetin for tobacco according to claim 1. 2+ method, It is characterized in that In step six, bismuth nanoparticle material is used to modify the electrode surface.

8. A method for detecting Pb in triacetin for tobacco according to claim 7. 2+ method, It is characterized in that In step six, the bismuth nanoparticle modified electrode adopts an in-situ modification method.

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